As an ink container to which the present invention is applied, an example of an ink cartridge mounted on an ink jet recording apparatus in a removable state will be explained. An ink jet recording apparatus generally has a pressure generation means for pressurizing a pressure generation chamber, a carriage in which an ink jet recording head having a nozzle opening for jetting pressurized ink from it as ink drops is loaded, and an ink container for storing ink to be fed to the recording head via a flow path and is structured so as to realize continuous printing. The ink container is generally structured as a cartridge attached to the recording apparatus in a removable state so as to be simply exchanged by a user at the point of time when ink is consumed.
Conventionally, as a control method for controlling the ink consumption of the ink cartridge, a method for calculating the count of ink drops jetted by the recording head and the ink amount sucked at the maintenance step of the recording head by software and controlling the ink consumption by calculation and a method for attaching two electrodes for liquid level detection directly to the ink cartridge, thereby detecting the point of time when a predetermined amount of ink is consumed actually and controlling the ink consumption are known.
However, in the method for calculating the jet count of ink drops and the sucked ink amount by software and controlling the ink consumption by calculation, depending on the use environment, for example, changes in the temperature and humidity in the room, the elapsed time after opening the ink cartridge, and differences in the use frequency on the user side, the pressure in the ink cartridge and ink viscosity are changed and an unnegligible error is often caused between the calculated ink consumption and the actual consumption. In this case, a problem arises that, although there is no ink actually, ink is calculated as if it still exists and detection of ink exhaust is delayed, or reversely, although there is still plenty of ink actually, ink is calculated as ink exhaust and ink is wasted. Furthermore, a problem also arises that even if a difference is generated between the calculated ink consumption and the actual ink consumption, it is difficult to correct it halfway. Further, a problem also arises that it is difficult to feed back changes in the ink characteristics due to the use environment to measurement of the subsequent ink consumption condition. Further, a problem also arises that when the same cartridge is removed once and mounted again, the calculated count is reset once, so that the actual ink residue cannot be known at all.
On the other hand, the method for controlling the point of time of ink consumption by the electrodes can detect the actual amount at a certain point of ink consumption, thereby can control the ink residue highly reliably. However, the ink level is to be detected, thus ink must be conductive, so that the kind of ink to be used is limited. Further, a problem arises that the liquid-tight structure between the electrodes and the ink cartridge is complicated. Furthermore, as a material of the electrodes, a highly conductive and corrosion-resistant noble metal is generally used, so that a problem also arises that the manufacturing cost of ink cartridges is increased. Furthermore, the two electrodes must be mounted respectively at different positions of the ink cartridge, so that a problem also arises that the number of the manufacturing steps are increased and the manufacturing cost is increased consequently.
Further, the conventional method for controlling the ink consumption of the ink cartridge detects the ink consumption even during recording of the recording head, so that the central processing unit (CPU) of the ink jet recording apparatus is used to detect the ink consumption condition, and the time to be used for recording by the CPU is reduced, and the recording speed is lowered. Further, in an on-carriage ink cartridge which is mounted on a carriage and moves together with the carriage, when the ink consumption condition is detected at the time of recording of the recording head, the ink cartridge itself and the ink in the ink cartridge vibrate and the ink consumption condition cannot be detected accurately.
Further, when a sensor for detecting the ink residue in the ink cartridge is attached in the ink cartridge, if the ink in the ink cartridge is consumed, the sensor detects that there is no ink in the ink cartridge.
However, even when the sensor detects that there is no ink in the ink cartridge, some amount of ink may remain in the ink cartridge. For example, ink may be collected or hardened in a complicatedly-shaped part of the groove or hole. Further, when air bubbles are attached in the neighborhood of the actuator or the sensor is attached to a position slightly above the bottom of the ink cartridge, if the ink level is below the mounting position of the sensor, the sensor detects absence of ink. In this case, a user cannot effectively use ink remaining in the ink cartridge.
Furthermore, the conventional control method for ink in the ink cartridge often measures the ink consumption condition always and unnecessarily. Further, regardless of the ink residue, the conventional method measures the ink residue at a uniform measuring interval, so that a problem arises that, when the measuring interval is long, the opportunity for detecting ink end at appropriate timing is lost.
Further, during and immediately after movement of the carriage, ink in the ink cartridge is often not in a rest state. Particularly, when the ink residue is small, the ink tends to wave. When the ink in the ink cartridge waves like this, during measurement of the ink consumption condition, ink makes or does not make contact with the measuring member. Therefore, a problem also arises that, although some ink remains still, ink end is detected by mistake, or although ink is almost exhausted, presence of ink is detected by mistake.
The present invention was made with the foregoing in view and is intended to provide an ink consumption condition detection method and an ink jet recording apparatus for detecting the ink residue accurately and requiring no complicated seal structure. Another object of the present invention is to provide an ink consumption condition detection method and an ink jet recording apparatus for detecting the ink consumption condition accurately without lowering the recording speed.
Further, the present invention provides an ink consumption condition detection method and an ink jet recording apparatus for effectively using ink remaining in the ink cartridge.
Further, the present invention is intended to provide an ink consumption condition detection method and an ink jet recording apparatus for effectively measuring the ink consumption condition and properly measuring the ink consumption condition without maldetection even if the ink residue is reduced.